title: [Demonstration of bone tissue in the axial skeleton of a chondrichthian: the dogfish (Scyliorhinus canicula)].
abstract: Dogfish vertebra have been studied by means of an undecalcified hard tissue method, including microradiography and tetracycline labelling. The transversal section of Dogfish vertebra shows a centrum and two couples of neural and hemal arches. The mineralized area consists of a narrow but continuous band, just against the perichondrium, formed by chondrocytes that participate in the surrounding matrix mineralization. The neural arches appear quite different: the upper parts contain hypertrophied cartilage and, close to it, the inner zones are formed by a crescent-shaped lamellar bone containing osteoblasts and osteocytes. A tetracycline label of these two types of hard tissue reveals a globular calcification with calcospherites and Liesegang rings, at the level of calcified cartilage and a strong and linear label of the inner border of the osseous tissue. The presence of osseous tissue in Elasmobranch endoskeleton is discussed in relation to, on one hand the evolution of the Gnathostomes skeleton and on an other hand the endocrinological point of view of calcium metabolism regulation in this group.
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000033:anatomy & histology*; D002356:Cartilage / Q000033:anatomy & histology; D004284:Dogfish / Q000033:anatomy & histology*; D005260:Female; D008297:Male; D008852:Microradiography; D012754:Sharks / Q000033:anatomy & histology*; D013131:Spine / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D013752:Tetracycline
chemical_list: D013752:Tetracycline
vernacular_title: Mise en évidence de tissu osseux dans le squelette axial d'un chondrichthyen : la rousette (Scyliorhinus canicula).